The aims of this study are twofold. One set of aims is 1) to obtain along ophtalmological documentation several types of measures of visual function which are especially sensitive to subtle outer retinal/pigment epithelial insult, for people of different ages and 2) to compare these measures for individuals having healthy eyes against those of individuals having eyes with macular drusen but normal acuity. The long term objective is 3) to evaluate these records (and their changes over time and interocular differences) for their ability to predict which eyes will eventually lose central vision due to exudative senile macular degeneration. The measures are 1) thresholds to slow flicker of short wavelength lights on longer wavelength backgrounds in order to measure blue cone sensitivity, 2) thresholds to rapid flicker of short and long wavelength lights in order to factor out the influence of pre-retinal absorptions, 3) time of recovery to a criterion sensitivity after a partial bleach and calculation of a rate constant of recovery, and 4) anomaloscopic measurements for large and small fields in order to detect receptor level abnormalities which cause a reduction in effective photopigment optical density. Ishihara plates, D-15 tests and Amsler grids will also be employed. Another set of aims is to pursue a series of basic researches designed 1) to ddtermine precisely red and green cone sensitivities across and entire visible spectrum with and without preretinal absorptions factored out, and to systematically investigate individual differences in these sensitivities, 2) to measure the effects of parameterized amounts of defocus upon sensitivities to slow and rapid flicker and 3) to evaluate for different types of sensitivity which portions of the retinal area under test are most responsible for detection of that test. The researches include studies of chromatic adaptation using 1)flicker photometry, 2) flicker thresholds, and an evaluation of the ability of these measures to predict 3) tritanopic color matches. The foveal flicker photometric measures will be repeated parafoveally for normals and compared interocularly for unilateral aphakes. The final study is of the directional dependence of several measures of sensitivity to a series of foverally centered annuli and discs. These researches bear directly on the formulation and interpretability of the aging studies.